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    SubjectRe: [PATCH -tip RFC 0/2] kprobes: introduce NOKPROBE_SYMBOL() and prohibit probing on .entry.text

    * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:

    > Currently the blacklist is maintained by hand in kprobes.c
    > which is separated from the function definition and is hard
    > to catch up the kernel update.
    > To solve this issue, I've tried to implement new
    > NOKPROBE_SYMBOL() macro for making kprobe blacklist at
    > build time. Since the NOKPROBE_SYMBOL() macros can be placed
    > right after the function is defined, it is easy to maintain.
    > At this moment, I applied the macro only for the symbols
    > which is listed in kprobes.c. As we discussed in previous
    > thread, if the gcc accepts to introduce new annotation to
    > store the function address (and size) at somewhere, we can
    > easily move onto that by replacing NOKPROBE_SYMBOL() with
    > nokprobe annotation (and just modifying the
    > populate_kprobe_blacklist() a bit).
    >
    > This series also includes a change which prohibits probing
    > on the address in .entry.text because the code is used for
    > very low-level sensitive interrupt/syscall entries. Probing
    > such code may cause unexpected result (actually most of
    > that area is already in the kprobe blacklist).
    > So I've decide to prohibit probing all of them.
    >
    > Since Ingo wasn't convinced about the idea in the previous
    > discussion, I just make this series as RFC series.
    > I'd like to ask again with actual implementation and plan.
    >
    > Thank you,
    >
    > ---
    >
    > Masami Hiramatsu (2):
    > kprobes: Prohibit probing on .entry.text code
    > kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist
    >
    >
    > arch/x86/kernel/entry_32.S | 33 ------------
    > arch/x86/kernel/entry_64.S | 20 --------
    > arch/x86/kernel/paravirt.c | 4 ++
    > include/asm-generic/vmlinux.lds.h | 9 +++
    > include/linux/kprobes.h | 19 +++++++
    > kernel/kprobes.c | 98 ++++++++++++++++++-------------------
    > kernel/sched/core.c | 1
    > 7 files changed, 80 insertions(+), 104 deletions(-)

    Ok, I like it after all.

    Mind changing over arch/x86/kprobes/* to use this new facility? There's no
    sense in kprobes internals using two types

    After that we can convert all the rest, probably as part of this series.

    There's a good reason now to do it: it's not just about cleanliness, it
    will also impact generated code less.

    Thanks,

    Ingo


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